1. Field of the Invention
The present invention relates to a dental root canal filling material that is heated for softening and filled in a root canal in the dental root canal treatment, and particularly, to a dental root canal filling material suitable for a root canal filling method in an obturation method.
2. Description of the Conventional Art
In general, as the therapy of dental pulp disease or apical periodontitis, there is carried out a root canal treatment in which, after pulpectomy, enlargement of root canal or root canal preparation is carried out, and a dental root canal filling material that is materially stable and is a stable substance to living bodies is filled in the obtained root canal, thereby keeping a root of the tooth harmless to a periodontal tissue. As this dental root canal filling material, those composed mainly of a gutta-percha and/or a balata, each of which is a natural resin, are generally used.
And, as a method for filling this dental root canal filling material in a root canal, are employed the following two modes:
(1) A lateral condensation method using a thin needle-like dental root canal filling material called a gutta-percha point; and
(2) An obturation method for softening a dental root canal filling material having a low softening temperature and filling it.
The lateral condensation method is a filling method using the gutta-percha point formed into a thin needle-like shape having a different thickness, which is composed mainly of gutta-percha and/or a balata and contains zinc oxide, calcium carbonate, beeswax, a wax, a resin, etc. In this lateral condensation method, first of all, a gutta-percha point called a main point, having the same size as in a reamer and a file to be used during the root canal preparation, is filled, and then, several thinner gutta-percha points called an accessory point are filled under pressure in a gap between the main point and the root canal wall.
However, in order to completely seal the root canal according to this method, a skill and a time period are required to a considerable degree. Further, in the case where the root canal is curved or branched, it is difficult to complete the filling to an apical portion.
On the other hand, the obturation method is a method in which a dental root canal filling material generally comprising a gutta-percha and/or a balata and a paraffin wax as basic components, whose heat softening temperature is lowered to about 40xc2x0 to 70xc2x0 C. by compounding an appropriate combination of zinc oxide, white Japan wax, beeswax, barium sulfate, titanium oxide, resins, etc. therewith, is heated for softening and filled. Since this dental root canal filling material is softened at a relatively low temperature to obtain fluidity, it can be poured and filled in the root canal by using a syringe, etc. Accordingly, this method has rapidly developed as a method in which the filling can be effected without influences by the root canal shape. The reason why the dental root canal filling material is regulated to have a heat softening temperature of about 40xc2x0 to 70xc2x0 C. is as follows. That is, when the heat softening temperature is lower than 40xc2x0 C., the setting becomes slow because that temperature is close to the oral cavity temperature, whereas when it exceeds 70xc2x0 C., a burn possibly occurs.
However, since in the dental root canal filling material that are currently used for this method, their softened materials are relatively hard and low in heat reserve properties, it cannot be said that the fluidity to the filling into the details such as an apical portion is sufficient. Further, inconveniences are likely generated such that the setting starts during the filling works, whereby the filling becomes incomplete, and that the root canal sealing property is inferior.
The present invention is aimed to provide a dental root canal filling material capable of overcoming the defects of the conventional dental root canal filling material are used in the current obturation method as described above, which is low in hardness and superior in fluidity with respect to its softened materials, and which has a performance suitable in the root canal filling operation in the obturation method with high heat reserve properties.
Under such a circumstance, the present inventor made extensive and intensive investigations with respect to components that, when compounded in even small amounts in a dental root canal filling material that is used in the current obturation method, can lower the hardness, increase the fluidity and improve the heat reverse properties in terms of its softened materials. As a result, it has been unexpectedly found that it is proper to compound bone wax therewith, leading to the development of a dental root canal filling material of the present invention.
Specifically, the dental root canal filling material according to the present invention is a dental root canal filling material to be used in a root canal filling method in an obturation method, which contains 3 to 8% by weight of bone wax and has a softening temperature of 40xc2x0 to 70xc2x0 C.
As constitutional components of the dental root canal filling material, with which the bone wax is to be compounded, according to the present invention, those used in a known dental root canal filling material having a heat softening temperature of 40xc2x0 to 70xc2x0 C., that is used in the root canal filling method in an obturation method, can be used. In general, known dental root canal filling material that can be used in the present invention comprises a gutta-percha and/or a balata and a paraffin wax as basic components and is compounded with an appropriate combination of zinc oxide, white Japan wax, beeswax, barium sulfate, titanium oxide, resins, etc. as well as other components such as zinc sulfide, eugenol, magnesium carbonate, various disinfectants, bactericides, pigments, etc.
The bone wax as referred to herein is a wax basically constituted by iodoform, spermaceti, and sesame oil, and having a melting point of 45xc2x0 C. or lower and a penetration index of 80 or more at 35xc2x0 C. A typical compounding ratio is one comprising 40% by weight of iodoform, 30% by weight of spermaceti, and30% by weight of sesame oil. In the case where such bone wax is combined with the known dental root canal filling material having a heat softening temperature of 40xc2x0 to 70xc2x0 C., that is used in the root canal filling method in an obturation method, there are effects for lowering the hardness and improving the fluidity as well as an effect for increasing the heat reserve properties, thereby prolonging the margin of time for filling operation, in terms of its softened material, without substantially lowering the heat softening temperature. Further, it is possible to easily fill root canals having even a complicated shape, such as a curved root canal and a branched root canal. Accordingly, the present invention can much improve the operability required in the root canal filling method in an obturation method.
A suitable amount of the bone wax that can be contained in the root canal filling material is 3 to 8% by weight. When the containing amount of the bone wax is less than 3% by weight, the effects of the bone wax are not exhibited sufficiently. On the other hand, when it exceeds 8% by weight, the softened material is too low in hardness and excessively high in fluidity, so that it is impossible to pressurize the composition sufficiently during the filling, whereby it is difficult to fill the composition into the narrow portions. Accordingly, the dental root canal filling material that is used in the root canal filling method in an obturation method, according to the present invention, is required to contain 3 to 8% by weight of bone wax and have a softening temperature of 40xc2x0 to 70xc2x0 C.
The dental root canal filling material according to the present invention will be described in detail with reference to the following Examples, but it is to be not construed that the invention is limited thereto.